In recent years, as an alternative for the conventional hydraulic brake, there has been developed an electric brake device designed to obtain braking force by pressing a friction-applying member, such as brake pad, against a friction-receiving member such as brake disk, with the aid of an electric actuator.
The brake device is a critical mechanism of vehicles, and employs a redundant system by which the vehicles can safely stop even in case of brake failure.
For example, Patent Literature 1 below discloses an electrically controlled brake system that includes a brake for limiting rotation of wheels, a power unit, and a brake control unit for controlling the operational state of the brake by controlling electric energy supplied from the power unit; the brake system further includes, disposed between the power source and the brake control unit, a switching device that performs switching from a connected state to a disconnected state in association with braking operation of a brake operating member; the brake control unit includes a switchover unit that toggles between a coupled mode in which the operation of a mechanical brake that operates in association with motion of a brake operating member is coupled to the brake operating member, and a decoupled mode in which the operation is decoupled from the brake operating member, and a switchover unit control unit that performs, in case of failure of the electrically controlled brake system, switching from the decoupled mode to the coupled mode.